Convergence system

ABSTRACT

In the static convergence for making a blue electron beam pass a point at which a red electron beam intersects with a green electron beam, a convergence system in which the static convergence operation is facilitate by preventing the magnetic force of the blue lateral magnet from adversely affecting the red and green electron beams at the time of operating the same magnet for driving the blue electron beam.

XR 397430985 SR O Umted States Patent 1 1 1 1 3,743,985 Nishimura et al. July 3, 1973 [54] CONVERGENCE SYSTEM 3,290,533 12/1966 Ammerman 335/212 I 3,533,031 10/1970 Sawada et a1 335/212 [751 lnvemrs= Nishimfm H Kalli 3,605,053 9/1971 Anthony 335/212 Mlchida, Morlsnchl; Koji Hiya, 3,516,038 6/1970 Hisamoto et al 335/212 Kadoma, all of Japan I [73] Assignee: Matsushita Electric Industrial Co.,

Ltd., Osaka, Japan Primary Examiner-George Harris Filed: J 1972 Attorney-Richard K. Stevens. Robert J. Frank et a1.

[21] Appl. No.: 261,399

[30] Foreign Application Priority Data [57] ABSTRACT June 18, 1971 Japan ..46/52600 June 22, 1971 Japan ..46/54329 In the Static Convergence for making a blue electron beam pass a point at which a red electron beam inter- 52 US. c1. 335/212, 3 13/77 sects withn green electron beam, a convergence system [51] Int. Cl. HOlf 1/00 in which the Static convergence Operation i facilitate 58 Field of Search 335/210, 212; y preventing the magnetic force of the blue lateral 313/75 77 magnet from adversely affecting the red and green electron beams at the time of operating the same-mag- 5 R f en Ci d net for driving the blue electron beam.

UNITED STATES PATENTS 3,290,532 12/1966 Lemke et a1 335/212 5 Claims, 19 Drawing Figures Patented July 3, 1973 '7 Sheets-Sheet l F l G. 3 PRIOR ART,

FIG. 5

Patented July 3, 1973 I 7 Sheets-Sheet 2 Patented July 3, '1973 '7 Sheets-Sheet 4 Patented July 3, 1973 7 Sheets-Sheet 5 FIG. I3

Patented July 3, 1973 v 7 Sheets-Sheet 6 Patnted July 3, 1973 3,743,985

7 Sheets-Sheet 7 1 CONVERGENCE SYSTEM The present invention relates to a convergence system mounted at the neck portion of a color television picture tube for correctly aiming the red, green and blue electron beams emitted from the electron gun, before they impinge on the front phosphor screen of the picture tube.

The objects, features and advantages of the present invention as compared with those of the prior art will be made apparent by the detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram schematically showing the structure of the blue lateral magnet portion employed in a conventional convergence system;

FIG. 2 is a diagram for explaining the operation of the convergence system shown in FIG. 1;

FIG. 3 shows the construction of another conventional convergence system;

FIGS. 4a and 4b are diagrams schematically showing the structure of the blue lateral magnet portion used in the convergence system embodying the present invention;

FIG. 5 is a diagram for explaining the operation of the convergence system shown in FIG. 4;

FIG. 6 is a side view showing an actual example of the same convergence system;

FIG. 7 is a front view thereof;

FIG. 8 is a side view of the blue lateral holder of the same convergence system;

FIG. 9 is a diagram showing the front view thereof;

FIG. 10 is a partially exploded perspective view of the same holder;

FIG. 11 is a disassembled perspective view of the same holder;

FIG. 12 is a diagram showing the general construction of the blue lateral magnet portion of a second embodiment of the present invention;

FIG. 13 is a diagram for explaining the operation of the convergence system shown in FIG. 12;

FIG. 14 is a partially exploded perspective view showing the actual construction of the blue lateral holder employed in the same convergence system;

FIG. 15 is a disassembled view of the same;

FIG. 16 is a diagram showing the general construction of the blue lateral magnet portion of a third embodiment of the present invention;

FIG. 17 is a diagram for explaining the operation of the third embodiment; and

FIG. 18 is a partially exploded perspective view of the blue lateral holder of the convergence system shown in FIG. 17.

Various prior art convergence systems have been developed. These prior art convergence systems function both as dynamic and static convergence each of which plays an important role.

In one of them, the blue lateral magnet portion for static convergence, as shown in FIG. 1, is rotatably arranged through the support metal 4 at a position opposite to the blue pole pieces 2 outside of the neck portion 1 of the picture tube.

The red, green and blue electron beams are separately controlled by static convergence magnets, while the static convergence is performed by rotating the blue lateral magnet 3. This operation is shown in FIG. 2. In this figure, first, the R (red) and G (green) electron beams are adjusted in the radial direction by rotating the static convergence magnets so that they intersect with each other at point W. Then the blue static convergence magnet is rotated and moved to the point nearest to point W, followed by the rotation of the blue lateral magnet 3 in order that the B (blue) beam intersects the R and G beams at point W.

In this case, however, magnetic fluxes of the blue lateral magnet 3 energizes even the R and G electron beams which had already intersected each other at point W, undesirably moving them away from the incoming B beam. This necessitates the renewed adjustment of the R and G beams, with the result that the three beams are finally converged at point W.

To overcome this difficulty, the convergence system as shown in FIG. 3 has been developed. On the neck portion 1 of the picture tube is mounted a rectangular guide frame 4', on both sides of which the blue lateral magnet 5 and the correcting magnet 6 are arranged through the support pieces 7. The support pieces 7 which are fitted in the spiral grooves 9 cut on the operating disc 8 cause the distance between the blue lateral magnet 5 and the correcting magnet 6 to be lengthened or shortened with the rotation of the operating disc 8, thereby to drive the B electron beam laterally. In other words, this system is intended to compensate for the adverse effect on the R and G electron beams due to the magnetic fluxes of the blue lateral magnet 5 by means of the correcting magnet 6.

In this type of convergence system, it is necessary for the blue lateral magnet 5 and the correcting magnet 6 to slide on the operating disc 8 in order to lengthen or shorten the distance between them and the neck portion 1, and therefore the diameter of the operating disc 8 has to be made inconveniently large, resulting in the bulkiness of the whole system and difficulty of operation of a purity magnet.

Accordingly, it is an object of the present invention to provide a compact convergence system which is simple in construction and easy to achieve static convergence.

Another object of the present invention is to provide a convergence system which employs a blue lateral magnet with a small magnetic power which requires adjustment over a very short distance for static convergence.

Still another object of the present invention is to provide a convergence system using a magnet of small magnetic power which prevents the deterioration of focusing or landing in a color television receiver for improved characteristics thereof.

A first embodiment of the invention will be explained now.

Referring to FIGS. 4a and 4b, the convergence system according to the present invention comprises a disc-shaped blue lateral magnet 10, a correcting magnet 11 and an operating disc 14 with spiral grooves 13. The blue lateral magnet 10 and the correcting magnet 11 which are rotatable around predetermined points are provided with a plurality of protrusions on their peripheries, which are fitted in the spiral grooves 13, so that by rotating the operating disc 14, only the blue beam is driven laterally utilizing the magnetic fluxes due to the magnets 10 and 11 which are magnetized in such a manner to be opposedly placed in the direction of the diameter of the operating disc.

In this embodiment, the R, G and B electron beams behave on the screen as shown in FIG. 5. In other words, the R and G electron beams are driven in the radial direction by operating the static convergence magnet to converge them at point W. The B electron beam is driven in the radial direction with the static convergence magnet to the point nearest to point W, followed by the rotation of the operating disc 14 to rotate the blue lateral magnet and the correcting magnet 11 whereby only the B electron beam is driven laterally to converge it with the other beams at point W.

The actual structure of the convergence system according to the present invention will be now explained with reference to FIGS. 6 to 10. I

The reference numeral 15 shows a convergence yoke of elastic polycarbonate or the like provided with three support frames 16, 17 and 18 radially arranged at equal angular intervals of 120 degrees. This convergence yoke 15 has at its central portion a cylindrical portion comprising three semi-circular pieces 19, into which the neck portion 20 of the picture tube is inserted. The semicircular pieces 19 are integrally coupled with the convergence yoke 15 by means of the elastic connecting pieces 21.

The support frames 16, 17 and 18 are provided with the dynamic convergence units 22, 23 and 24 respectively for the R, G and B electron beams, and on the outer ends of the dynamic convergence units 22, 23 and 24 are rotatably mounted the disc-like static convergence magnets 25, 26 and 27 respectively.

In addition a connecting portion 28 is formed between adjacent elastic connecting pieces 21 and coupled with the blue lateral holder as will be described later.

In addition to the convergence yoke 15, a blue lateral holder 29 is provided which is comprised of three cylindrical portions, one of which, i.e. the large-diameter cylindrical portion 30 has a plurality of longitudinally projected integral engaging protrusions 31 for engage ment with the convergence yoke 15. Also, on the periphery of the large-diameter cylindrical portion 30 are formed a plurality of protrusions 32 which hold the annular purity magnet 33. Numeral 37 shows a mounting portion on which the blue lateral magnet 35 and the correcting manget 36 are rotatably mounted, the mounting portion 37 extending from the outer upper surface of the large-diameter cylindrical portion 30 to the medium-diameter cylindrical portion 34. Each of the two magnets 35 and 36 comprises a cap 39 of syn thetic resin with a plurality of engaging protrusions 38 arranged at equal intervals on the outer periphery thereof, and a ring-shaped magnet 41 with an aperture in which one of the rotational axles is fitted, the magnet 41 being magnetized in such a manner that its poles are located opposedly to each other in the direction of the diameter on the periphery of the magnet 41. v

The mounting portion 37 which supports the rotatable blue lateral magnet 35 and correcting magnet 36 is provided with a recess 42 to receive the rotational axle 40 and an opening 43 in which the magnets 35 and 36 are fitted. On the periphery of the medium-diameter cylindrical portion 34 are a plurality of hooks 48. Between the hooks 48 and the upper surface of the mounting portion 37 is rotatably inserted an operating disc 44 with two spiral grooves which is knurled on the outer periphery thereof. The engaging protrusions 38 of the magnets 35 and 36 are fitted in the spiral grooves. Also, a magnetic pole plate 49 is arranged on the inside of the mounting portion 37 of the correcting magnet 36 so that magnetic fluxes therefrom may act on the red and green pole pieces. The small-diameter cylindrical portion 45 is of such a size that it exactly fits on the neck portion 20 of the picture tube. This smalldiameter cylindrical portion 45 is fitted with the fastening metal 46. The reference numeral 47 shows a fastening metal fitted in the three semi-circular pieces 19 of the convergence yoke 15.

The convergence system is completed by combining the convergence yoke 15 with the above-described structure and the blue lateral holder 29. The adjustment of static convergence of this system is performed in the manner explained above with reference to the operation thereof.

Another embodiment of the invention will be now explained with reference to FIG. 12 showing the principle of operation thereof.

The reference numeral 50 shows a neck portion of the picture tube through which the blue beam 51, red beam 52 and green beam 53 pass. Blue lateral magnets 54 and are arranged at positions near the neck portion 50 along intermediate axes between the blue beam 51 and red beam 52 and between the green beam 53 and the blue beam 51 respectively. Each of the blue lateral magnets 54 and 55 has a synthetic resin covering 57 with a plurality of protrusions formed at regular intervals around it. The blue lateral magnets 54 and 55 are rotated with the protrusions 56 being fitted in the operating disc 59. From these blue lateral magnets 54 and 55 are extended almost L-shaped magnetic pole plates 60 and 61 respectively as far as the axis of the blue beam 51, so that the magnetic fluxes due to the blue lateral magnets 54 and 55 are divided into those portions corresponding to the blue beam 51, red beam 52 and green beam 53.

The action of each electron beam is as shown in FIG. 13. First, static convergence between the red beam 52 and green beam 53 is achieved. Then the operating plate 59 is driven to rotate the blue lateral magnets 54 and 55, thereby causing the blue beam 51 to approach point A where the red and green beams intersect with each other. At this time, the red beam 52 and green beam 53 move in such a direction as to receive the blue beam 51. In this way, the system is adjusted for static convergence, resulting in the three beams intersecting at point B.

An actual example of the preceding embodiment is shown in FIGS. 14 and 15. The reference numeral 63 shows a holder of synthetic resin adapted to be fitted in the neck portion 50. The holder 63 is provided with the portion 65 to receive the purity magnet 64, a mounting portion 66 where the blue lateral magnets 54 and 55 are mounted, a protrusion 67 with which the operating disc 59 engages, and a protrusion 68 where the magnetic pole plates 60 and 61 are fitted. A fastening ring 70 is fitted in the small-diameter portion 69 and fixed on the neck portion 50.

Explanation will be made now of a third embodiment of the present invention with reference to FIG. 16 showing the principle on which it is operated.

The reference numeral shows a neck portion of the picture tube, through which the blue beam 81, red beam 82 and green beam 83 pass. The numeral 84 shows a blue lateral magnet disposed along the central axis of the blue beam on the periphery of the neck portion 80. This blue lateral magnet 84 has around it a plurality of protrusions spaced at regular intervals. The blue lateral magnet 84 may alternatively consist of an inside magnet and a cap covered on it and having a plurality of protrusions 85 on the periphery thereof.

Outside of the blue lateral magnet 84 is arranged a magnetic pole plate comprising a circular arc section 86 extending over about 120 degrees and a couple of inwardly bent portions 87 which are radially arranged at the ends of the magnetic pole plate 88. One of the bent portions 87 is in contact with that part of the neck portion 80 intermediate between the blue beam 81 and red beam 82, and the other thereof that part of neck portion 80 between blue beam 81 and green beam 83.

The blue lateral magnet with the above-mentioned structure is rotated with the operating disc 90 having narrow spiral grooves 89 formed on the underside thereof. In other words, the blue lateral magnet 84 rotates when the operating disc 90 is rotated with the protrusions 85 of the blue lateral magnet 84 engaged with the grooves 89.

In this arrangement, the red beam 82 and green beam 83 are made to intersect each other for static convergence, and then the blue beam 81 is driven in a radial direction to the point nearest to point A at which the red beam 82 and green beam 83 intersects, followed by the operation of the operating disc 90 to deflect the blue beam laterally. In the meantime, not only the magnetic fluxes due to the blue lateral magnet 84 act on the blue beam 81 but the magnetic pole plate 88 forms magnetic fluxes to affect the red beam 82 and green beam 83, so that the blue beam is drawn toward the intersection between the red and green beams. Under this condition, the red and green beams are driven to achieve static convergence at point B.

It will be understood from the above explanation that according to the present invention static convergence of the three beams is easily and accurately accomplished.

This embodiment comprises, as shown in FIG. 18, a holder 91 of synthetic resin fitted on the neck portion 80 of the picture tube, supports 99 for holding the purity magnet 92 on the peripheral portions of the holder, a mounting portion 93 for holding the blue lateral magnet 84, an engaging piece 94 for holding the magnetic pole plate 88, an engaging piece 95 for holding the adjusting plate 90, the toe 96 for engagement with the convergence board on the underside, and a fastening ring 99 fitted in the upper small-diameter portion 97.

The convergence system with the above-described structure hasa correcting magnet which is disposed rotatably without any other movements to offset the adverse effect of the magnetic fluxes due to the blue lateral magnet. This correcting magnet is driven by the operating disc to deflect the blue electron beam laterally. Therefore, it is possible to make the operating disc smaller. In addition, the two magnets can be reduced in size because of their proximity to the neck portion of the picture tube, resulting in a lower cost of the convergence system.

Furthermore, since the red and green electron beams are not adversely affected by the blue lateral magnet, the quantity of magnetic fluxes used for adjustment is minimized, thus eliminating any deterioration of the picture which otherwise might occur by the blue lateral adjustment.

Also, fine adjustment is possible by properly selecting the number of the spiral grooves and the engaging protrusions and their pitches, thus contributing to an increased commercial value.

According to the present invention, rotatable blue lateral magnets are arranged along the intermediate axis between the blue and red beams and between the blue and green beams respectively, and from these blue lateral magnets extend L-shaped magnetic pole plates to a point on the central axis of the blue electron beam path. For these reasons, lateral correction is performed in a very short distance, making it possible to employ a blue lateral magnet of very small magnetic power. This feature is also utilized to great advantage in eliminating the deterioration of focusing or landing.

Still another commercial advantage of the present invention consists in very easy adjustment, which permits assemblage and adjustment of the color television receiver in a very short time.

Moreover, according to the present invention, a rotatable blue lateral magnet is arranged at a position nearest to the blue beam in the neck portion of a picture tube which contains blue, red and green beams arranged symmetrically with respect to a point, and this magnet has a magnetic pole plate comprising a semicircular portion extending over about degree on the peripheral portion of the magnet and inwardly bent portions at the ends thereof, thereby greatly facilitating the adjustment of static convergence and shortening the distance required for correction of each beam. In addition, the blue lateral magnet can be made smaller in magnetic power for a lower production cost.

The above-mentioned advantages permit the elimination of the deterioration of focus and landing, thus improving the characteristics and practical value of the convergence system.

What we claim is:

l. A convergence system comprising a mount portion fixed on the neck portion of a color picture tube having three electron guns arranged symmetrically with respect to a point, a plurality of dynamic convergence units and static convergence units arranged on the periphery of said mount portion, a blue lateral magnet mounted on a portion of said mount portion for driving a blue electron beam in a lateral direction, and an operating disc with a plurality of spiral grooves cut thereon, said blue lateral magnet being rotatable by means of said spiral grooves on said operating disc without any linear movement thereby to control the magnetic power applied to the blue electron beam, said magnetic power of said blue lateral magnet producing final static convergence of the red, green and blue beams.

2. A convergence system according to claim 1, in which said blue lateral magnet is rotatable around a central rotational axis thereof, said blue lateral magnet having on the periphery thereof a plurality of protrusions for engagement with one of said spiral grooves of said operating disc, said blue lateral magnet being fixed on part of said mount portion of the picture tube.

3. A convergence system according to claim 1, in which said blue lateral magnet is rotatable around a central rotational axis thereof and has on the periphery thereof a plurality of protrusions for engagement with one of said spiral grooves of said operating disc, said blue lateral magnet being fixed on part of said mount portion of the picture tube, said convergence system further comprising a rotatable correcting magnet of the same structure as said blue lateral magnet, said correcting magnet being disposed opposedly to said blue lateral magnet, said correcting magnet counteracting the magnetic power of said blue lateral magnet applied to the red and green beams.

4. A convergence system according to claim 1, comprising a pair of blue lateral magnets adapted to rotate on axes intermediate between blue and red beams and between blue and green beams respectively by means of an operating disc, said blue, red and green electron beams passing through said neck portion of the picture tube, a pair of substantially L-shaped magnetic pole plates extending from said blue lateral magnets to the central axis along which the blue beam passes, said pair of blue lateral magnets being used to drive the blue beam, the red and green beams being deflected toward the blue beam in response to the lateral adjustment of the blue beam.

5. A convergence system according to claim 1, comprising a blue lateral magnet positioned nearest to the blue beam, an operating disc for rotating said blue lateral magnet, and an L-shaped magnetic pole plate including a semi-circular portion extending over the angle of about and end portions bent inwardly in a radial direction, said semi-circular portion of said channel-shaped magnetic pole plate being positioned on the peripheral portion of said blue lateral magnet, the magnetic power of said blue lateral magnet being used for lateral adjustment-of the blue beam, the red and green beams being driven toward the blue beam in response to said lateral adjustment of the blue beam. 

1. A convergence system comprising a mount portion fixed on the neck portion of a color picture tube having three electron guns arranged symmetrically with respect to a point, a plurality of dynamic convergence units and static convergence units arranged on the periphery of said mount portion, a blue lateral magnet mounted on a portion of said mount portion fOr driving a blue electron beam in a lateral direction, and an operating disc with a plurality of spiral grooves cut thereon, said blue lateral magnet being rotatable by means of said spiral grooves on said operating disc without any linear movement thereby to control the magnetic power applied to the blue electron beam, said magnetic power of said blue lateral magnet producing final static convergence of the red, green and blue beams.
 2. A convergence system according to claim 1, in which said blue lateral magnet is rotatable around a central rotational axis thereof, said blue lateral magnet having on the periphery thereof a plurality of protrusions for engagement with one of said spiral grooves of said operating disc, said blue lateral magnet being fixed on part of said mount portion of the picture tube.
 3. A convergence system according to claim 1, in which said blue lateral magnet is rotatable around a central rotational axis thereof and has on the periphery thereof a plurality of protrusions for engagement with one of said spiral grooves of said operating disc, said blue lateral magnet being fixed on part of said mount portion of the picture tube, said convergence system further comprising a rotatable correcting magnet of the same structure as said blue lateral magnet, said correcting magnet being disposed opposedly to said blue lateral magnet, said correcting magnet counteracting the magnetic power of said blue lateral magnet applied to the red and green beams.
 4. A convergence system according to claim 1, comprising a pair of blue lateral magnets adapted to rotate on axes intermediate between blue and red beams and between blue and green beams respectively by means of an operating disc, said blue, red and green electron beams passing through said neck portion of the picture tube, a pair of substantially L-shaped magnetic pole plates extending from said blue lateral magnets to the central axis along which the blue beam passes, said pair of blue lateral magnets being used to drive the blue beam, the red and green beams being deflected toward the blue beam in response to the lateral adjustment of the blue beam.
 5. A convergence system according to claim 1, comprising a blue lateral magnet positioned nearest to the blue beam, an operating disc for rotating said blue lateral magnet, and an L-shaped magnetic pole plate including a semi-circular portion extending over the angle of about 120* and end portions bent inwardly in a radial direction, said semi-circular portion of said channel-shaped magnetic pole plate being positioned on the peripheral portion of said blue lateral magnet, the magnetic power of said blue lateral magnet being used for lateral adjustment of the blue beam, the red and green beams being driven toward the blue beam in response to said lateral adjustment of the blue beam. 